DUBAI — Iran said Thursday that it executed a prisoner convicted of a crime committed during ongoing nationwide protests, the first such death sentence carried out by Tehran.

The execution comes as other detainees also face the possibility of capital punishment for their involvement in the protests, which began in mid-September as an outcry against Iran’s morality police. The protests have since expanded into one of the most serious challenges to Iran’s theocracy since the 1979 Islamic Revolution.

Activists warn that others could also be put to death in the near future, saying that at least a dozen people so far have received similar sentences over their involvement in the demonstrations.

Iran’s Mizan news agency reported the execution of the man, identified as Mohsen Shekari. It accused Shekari of blocking a street in Tehran and attacking a member of the security forces with a machete. The target required stitches for his wounds, the agency said.

Mahmood Amiry-Moghaddam, director of the Oslo-based activist group Iran Human Rights, wrote that the “execution of #MohsenShekari must be [met] with STRONG reactions otherwise we will be facing daily executions of protesters. This execution must have rapid practical consequences internationally.”

German Foreign Minister Annalena Baerbock condemned Shekari’s execution in a Twitter post, saying that “the Iranian regime’s contempt for humanity is limitless.”

The Mizan report also alleged that Shekari admitted being offered money to attack the security forces. The government for months has alleged — without offering evidence — that foreign countries have fomented the unrest. Protesters say they are angry over the collapse of the economy, heavy-handed policing and the entrenched power of the country’s Islamic clergy.

Mizan said Shekari was arrested Sept. 25, then convicted Nov. 20 on the charge of “moharebeh,” a Persian word meaning “waging war against God.”